/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 *
 * http://www.gnu.org/copyleft/gpl.html
 */
package com.dream.tools.security;

import java.net.InetAddress;
import java.nio.channels.SocketChannel;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map.Entry;

import com.dream.mmocore.IAcceptFilter;

public class IPv4Filter implements IAcceptFilter, Runnable
{
	protected static final class Flood
	{
		long lastAccess;
		int trys;

		Flood()
		{
			lastAccess = System.currentTimeMillis();
			trys = 0;
		}
	}

	private static final long SLEEP_TIME = 5000;

	private static final int hash(byte[] ip)
	{
		return ip[0] & 0xFF | ip[1] << 8 & 0xFF00 | ip[2] << 16 & 0xFF0000 | ip[3] << 24 & 0xFF000000;
	}

	private final HashMap<Integer, Flood> _ipFloodMap;

	public IPv4Filter()
	{
		_ipFloodMap = new HashMap<>();
		Thread t = new Thread(this);
		t.setName(getClass().getSimpleName());
		t.setDaemon(true);
		t.start();
	}

	@Override
	public boolean accept(SocketChannel sc)
	{
		InetAddress addr = sc.socket().getInetAddress();
		int h = hash(addr.getAddress());

		long current = System.currentTimeMillis();
		Flood f;
		synchronized (_ipFloodMap)
		{
			f = _ipFloodMap.get(h);
		}
		if (f != null)
		{
			if (f.trys == -1)
			{
				f.lastAccess = current;
				return false;
			}

			if (f.lastAccess + 1000 > current)
			{
				f.lastAccess = current;

				if (f.trys >= 3)
				{
					f.trys = -1;
					return false;
				}

				f.trys++;
			}
			else
			{
				f.lastAccess = current;
			}
		}
		else
		{
			synchronized (_ipFloodMap)
			{
				_ipFloodMap.put(h, new Flood());
			}
		}

		return true;
	}

	@Override
	public void run()
	{
		while (true)
		{
			long reference = System.currentTimeMillis() - 1000 * 300;
			synchronized (_ipFloodMap)
			{
				Iterator<Entry<Integer, Flood>> it = _ipFloodMap.entrySet().iterator();
				while (it.hasNext())
				{
					Flood f = it.next().getValue();
					if (f.lastAccess < reference)
					{
						it.remove();
					}
				}
			}
			try
			{
				Thread.sleep(SLEEP_TIME);
			}
			catch (InterruptedException e)
			{
				return;
			}
		}
	}

}